My friend walked me to the bus stop and waited with me______________ the bus arrived.
A.once B.unless C.when D.until
My umbrella is gone. Who ______________ have taken it by mistake?
A.could B.should C.would D.must
Car races are recorded and uploaded to YouTube and other video platforms, ______________ they can be viewed repeatedly.
A.which B.where C.when D.there
Eager readers can check with libraries ______________ if they have people interested in book discussion.
A.seeing B.see C.to see D.to have seen
My teacher never criticizes us. Instead, he uses praise to ______________ our best.
A.bring out B.take on
C.jump off D.figure out
When the sun’s rays hit the earth, a lot of heat ______________ back into space
A.are reflected B.is reflected
C.reflects D.were reflected
